Nested Loops

Nested loops are loops inside loops. They allow us to perform operations on multi-dimensional data structures or execute repeated actions within an iterative process. Practice these problems to strengthen your understanding of nested loops.

Practice Problems

Problems Index

Print a square pattern of * with n rows and columns.
Print a right-angled triangle pattern of *.
Generate a multiplication table up to n.
Create a pyramid pattern of numbers.
Print the following pattern for n:
```
1
12
123
1234
```
Input a list of lists and calculate the sum of all elements.
Print all pairs of elements from two lists.
Find the transpose of a 2D matrix.
Print a pattern where each row contains numbers from 1 to the row number.
Generate a checkerboard pattern with alternating 0 and 1.

Try It Yourself

Now that you’ve reviewed the problems, practice them below using the code runner!

Pyground

Play with Python!

Output:

Solutions

Print a square pattern of * with n rows and columns.

Show Code

n = int(input("Enter the size of the square: "))
for i in range(n):
    for j in range(n):
        print("*", end=" ")
    print()

Print a right-angled triangle pattern of *.

Show Code

n = int(input("Enter the height of the triangle: "))
for i in range(1, n + 1):
    print("*" * i)

Generate a multiplication table up to n.

Show Code

n = int(input("Enter the table size: "))
for i in range(1, n + 1):
    for j in range(1, n + 1):
        print(f"{i * j:4}", end=" ")
    print()

Create a pyramid pattern of numbers.

Show Code

n = int(input("Enter the height of the pyramid: "))
for i in range(1, n + 1):
    print(" " * (n - i) + " ".join(str(x) for x in range(1, i + 1)))

Print the following pattern for n:

Show Code

n = int(input("Enter the number of rows: "))
for i in range(1, n + 1):
    for j in range(1, i + 1):
        print(j, end="")
    print()

Input a list of lists and calculate the sum of all elements.

Show Code

matrix = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
total = 0
for row in matrix:
    for num in row:
        total += num
print("Total sum:", total)

Print all pairs of elements from two lists.

Show Code

list1 = [1, 2, 3]
list2 = ['a', 'b', 'c']
for item1 in list1:
    for item2 in list2:
        print(f"({item1}, {item2})")

Find the transpose of a 2D matrix.

Show Code

matrix = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
transpose = []
for i in range(len(matrix[0])):
    row = []
    for j in range(len(matrix)):
        row.append(matrix[j][i])
    transpose.append(row)
print("Transpose of the matrix:", transpose)

Print a pattern where each row contains numbers from 1 to the row number.

Show Code

n = int(input("Enter the number of rows: "))
for i in range(1, n + 1):
    for j in range(1, i + 1):
        print(j, end=" ")
    print()

Generate a checkerboard pattern with alternating 0 and 1.

Show Code

n = int(input("Enter the size of the checkerboard: "))
for i in range(n):
    for j in range(n):
        print((i + j) % 2, end=" ")
    print()

While Loop Handling Strings